Second Nephi 8:11

Therefore, the redeemed of the Lord shall return, and come with singing unto Zion; and everlasting joy and holiness shall be upon their heads; and they shall obtain gladness and joy; sorrow and mourning shall flee away.

Isaiah prophesies of the time when the Jews will be released from bondage and return to their homeland. As great as will be their joy and rejoicing at their liberation, their temporal salvation is only temporary. Greater yet will be our everlasting joy and eternal gladness when we are redeemed, not from our temporal bondage, but from our spiritual bondage. When Israel is gathered for the last time at the Second Coming of Christ, they will return not just to their earthly homeland but to their heavenly home, which is the kingdom of God, embodied in Zion. Their joy will then be uninterrupted. They will then experience true gladness and a fullness of joy. Sorrow and mourning for sin will flee away by the power of the atonement, which brings about mercy, forgiveness, and pardon. When guilt is swept away, mourning will cease.

Second Nephi 8:9

Awake, awake! Put on strength, O arm of the Lord; awake as in the ancient days. Art thou not he that hath cut Rahab, and wounded the dragon?

Isaiah interjects a prayer to Jehovah to call forth the Messiah, who is the arm of the Lord. Isaiah pleads for the Messiah to arise and come to the defense of His people. Isaiah has seen that Christ will vanquish the devil, just as He will defeat the king of Babylon, just as he defeated Pharaoh and freed captive Israel from Egyptian slavery. Over and over God has rescued His children from temporal captivity. He will do so again and again. But these deliverances are only symbols of the eternal deliverance that Christ ultimately performs for all through the ransom of the atonement, which brings about redemption from sin. The ultimate enemy is not an earthly king but Satan. Just as God performs miracles to defeat His worldly enemies, He will employ the miracle of the atonement to defeat His spiritual adversary, who is truly the enemy of our souls.